Filter press

ABSTRACT

A press for expressing liquids from solids or for forming moulded blocks comprises a frame including a facing pair of upper and lower platens, a filter cloth extending across the lower platen, and a fluid expansible bellows device located between the platens and serving to press material against the filter cloth. The bellows device is comprised by the novel arrangement of a first flexible diaphragm connected to the upper platen and forming a fluid chamber with the upper platen, and an inflatable bag member between said first flexible diaphragm and the lower platen. The inflatable bag has an upper diaphragm wall back-to-back with said first diaphragm and a lower diaphragm wall for pressing material on the filter cloth, the inflatable bag and the fluid chamber being in fluid communication; and the bellows device includes an inlet for pressure fluid.

United StatesPatent [1 1 Davidson FILTER PRESS [75] Inventor; Maxwell Wingate Davidson,

Edinburgh, England [73] Assignee: Maxwell Davidson Limited,

Edinburgh, Great Britain [22] Filed: May 24, 1972 [21] Appl. No.: 256,248

[52] US. Cl 425/84, 100/118, 100/211, 425/389 [51] Int. Cl. B29c 3/00 [58] Field of Search 425/406, 389, 408, 84; I

[56] References Cited UNITED STATES PATENTS 2,671,493 3/1954 Olson 100/211 X 2,931,290 4/1960 Davidson t 100/211 3,156,958 ll/l964 Miller et al. 100/211 X 3,661,683 5/1972 Engel et al...... 100/211 X Gunkel 100/118 [111 3,825,382 1- July 23, 1974 Primary ExaminerRobert L. Spicer, Jr. Attorney, Agent, or Firm-Young & Thompson [5 7 ABSTRACT A press for expressing liquids from solids or for forming moulded blocks comprises a frame including a facing pair of upper and lower platens, a filter cloth extending across the lower platen, and a fluid expansible bellows device located between the platens and serving to press material against the filter cloth. The bellows device is comprised by the novel arrangement of a first flexible diaphragm connected to .the upper "platen and forming a fluid chamber with the upper platen, and an inflatable bag member between said first flexible diaphragm and the lower platen.

The inflatable bag has an upper diaphragm wall back-to-back with said first diaphragm and a lower diaphragm wall for pressing material on the filter cloth, the inflatable bag and the fluid chamber being in fluid communication; and the bellows device includes an inlet for pressure fluid 21 Claims, 4 Drawing Figures n II This invention relates to a press and particularly a filter press for expressing liquids from materials.

According to the present invention there is provided a press comprising a frame structure including a facing pair of spaced platens having facing surfaces; a receiving medium for material to be pressed extending across the facing surface of one of the platens, a fluid expansible device located between the platens and including a first flexible diaphragm connected to the other of the platens and forming a fluid chamber with said other platen, and an inflatable member between the first diaphragm and said one platen and comprising a second flexible diaphragm back-to-back with said first diaphragm and a third flexible diaphragm for pressing material on the receiving medium, the inflatable member and fluid chamber being in fluid communication; and inlet means to the expansible device for pressure fluid.

Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings in which:

FIG. 1 shows a side view of a press for forming concrete wall panels;

FIG. 2 shows a plan view of the pressof FIG. 1 together with a conveyor band passing through the press;

FIG. 3 shows a cross-sectional view of the diaphragm and ring arrangement between the sections of the press of FIG. 1; and

FIG. 4 shows filter press apparatus including a press of the type shown in FIG. 1. 1

Referring to FIGS. 1-3, in one embodiment of the present invention, a filter press is provided for the press moulding of concrete or other cementitious blocks for use in construction work, for example, the erection of buildings.

The press 1 comprises generally a frame which is formed with top 2 and bottom 3 sections, each of which is a hollow metal box fabrication of girders 4 and plates 5. The two sections 2, 3 are spaced vertically one above the other, and are supported along two parallel sides by upstanding columns 6, bolted to the sections 2, 3. Thus an open-ended through passage 7 is defined between the two spaced sections 2, 3 and the columns 6.

The facing portions 8, 9 of the two sections 2, 3 each comprise a metal plate. An intermediate metal ring 10 (FIG. 3) is positioned within the passage 7 and attached to the upper section 2 by means of a number of pressure fluid operated ram devices 11, whereby the ring 10 can be moved towards or away from the upper plate 8. Interposed between the ring 10 and the upper plate 8 are two back-to-back flexible inflatable diaphragms 12, 13, clamped to the plate 8 and the ring 10 respectively, by clamping rings 14, the diaphragms 12, 13 abutting one another but having a centrally located connection port 15 to provide fluid communication therebetween. The-diaphragm 13 is clamped to the ring 10 around the outer periphery thereof, so that an inwardly projecting shoulder 18 is provided on the ring 10. The space defined between the upper plate 8 and the diaphragm 12 attached to that plate 8 is provided with an inlet pipe 16 leading through the top section 2 for the supply and discharge of pressure fluid. The connection port 15 between the two diaphragms 12, 13,

has a peripheral metal flange 17 on each diaphragm,

the two flanges 17 being bolted together.

A third flexible inflatable diaphragm 19 is provided, this one being clamped to the ring 10 by clamp 14, and arranged, when inflated, to protrude through the ring gap 20 (FIG. 3) towards the lower plate 9. A peripheral wall member 21, or mould, having an appropriately profiled inner peripheral wall 22 is positioned beneath the ring 10 and is located at a moulding station on a drainage bed formed by a perforated metal conveyor belt 23 which rests on the lower metal plate 9. The top surface of the lower plate 9 is grooved for drainage of any liquids expressed during the pressing operation which occurs upon inflation of the diaphragms 12, 13, 19, by the admission of pressure fluid.

A pressure chamber 24 is defined by the profiled inside wall 22 of the mould 21, the perforated belt 23 and the lower surface of the third diaphragm 19.

The conveyor belt 23 extends out beyond the press passage 7 on both sides of the press 1 (see FIG. 3), and

is in the form of an endless band entrained around end drums 25, 26, with a drive motor unit 27 provided for progressing the belt 23, so as to move the belt 23 into, through and out of the press chamber 24 in the desired direction and to the desired extent.

The mould member 21 has a rubber insert sealing member 28 on its underside, and is held in contact with the conveyor belt 23 and the bottom section 3 by the action of therams 11, which space the ring from the upper metal plate and by the effect of the pressure fluid inflating the three diaphragms and acting on the shoulder 18. The grooves (not shown) on the upper surface of the lower metal plate 9 communicate with drainage channels (not shown) running along the sides of the press 1. Additionally, the ring member 10 has itself a resilient rubber insert 29 on its underface to facilitate a sealing engagement within the wall member 21 during the pressing operation.

Outwith the press passage 7 on either side of the conveyor belt a plurality of pressure fluid operated rams (not shown) are provided, these being intended to engage the wall or mould member 21 after it has been moved out of the press chamber 1 after the press operation has been effected,to separate the wall or mould member 21 from the press moulded block which can then be conveyed away to futher treatment, e.g. storage for curing. Retraction of the rams will then return the wall or mould member 21 on to the conveyor belt 23, and a fresh charge of the cementitious material to be pressed can be filled into the area bounded by the member 21, and the wall member 21 with cementitious charge material conveyed back into the press passage The press can operate alternately to discharge a press formed block at either side so that whilst one formed block is discharged another one is being formed within the press. I

Also, a pair of filter cloths may be provided between the third diaphragm 19 and the conveyor belt 23, and forms an envelope, the wall member 21 being positioned between the filter cloths. The filter cloths are preferably in the form of endless belts and more appropriately with the conveyor belt 23.

Referring to FIG. 4, in a second embodiment of the present invention, apparatus is provided for the expression of liquids from materials such as slurries so that either the material or the liquid can be reclaimed. The

apparatus includes a press, similar to that of the first embodiment, similar parts being referred to by the same numerals; however in this case it may be desired to pass the material to be treated into the pressing chamber 24 (FIG. 3) within the press itself rather than filling the charge outwith the press passage 7. Thus in this case suitable inlets 30 are provided through the wall member 21. These inlets 30 are connected to a slurry supply pipe 31 by flexible conduits 32. Also, the lower plate 9 which is plane carries a ribbed rubber block 33 for drainage of the filtrate; and a pair of endless filter cloth bands 34,35 form an envelope between the third diaphragm 19 and the rubber block 33, the pressure chamber 23 being defined by the inside wall 22 and the two filter cloths 34, 35. The undersurface of the-third diaphragm 19 is grooved for drainage of liquids expressed during the pressing operation. The wall member 21 which is positioned between the filter cloths 34, 35 is provided with side apertured lugs 36, through which respective rams 37 of the devices 11 project, the heads of each of these rams 37 being in the form of a stirrup 38 for engagement with the lugs 36, whereby, after the pressing operation has been effected, and upon deflation of the diaphragms 12, 13, 19, and retraction of the ring towards the upper plate 7, the wall member 21 will automatically be lifted out of contact with the lower filter cloth 35 to permit this cloth with the caked solids on it to be conveyed away out of the press passage 7. Also, the retraction of the ring 10 causes sufficient relative displacement between the ring and the wall member 21 to enable the upper filter cloth 34 to move out of the press passage 7.

Each of the endless filter cloth bands 34, 35, which are trained around a plurality of rollers 39, has ancillary equipment associated therewith, this ancillary equipment and rollers 39 being mounted on an upstanding support structure 40 together with the press 1. The ancillary equipment includes a pulleydrive for the bands 34, 35 comprising a vertically reciprocal guide member 41 having a pair of opposed rllers39 around which are trained oppositely extending lengths of filter cloth, .a piston-and-cylinder actuator 41A for the member 41 and a clamp 46 for the cloth to permit progressive movements of the cloth; a brushing device 42 for removal of excess slurry from the band and a discharge chute 43 located below the device 42; an additional cloth washing assembly 44; and a controller 45 for regulating each advance of the endless cloth position. Pipelines 47, 48 are located to receive filtrate passing from the diaphragm 19, the ring including apertures in its peripheral wall for fluid communication between the grooves in the bottom surface of the diaphragm l9 and the pipelines 47, and from the ribbed block 33 respectively, and may discharge the filtrate to a suitable receiver (not shown).

In operation of the filter press apparatus, the ram devices 11 are actuated to move the ring 10 downwards, and the diaphragm assembly 12, 13, 19 is given a preliminary pressurisation, this pressure being determined by the capacity of the pump delivering slurry to the press 1 and by the required filtration pressure. A charge of slurry isdelivered through the inlets 30 from pipe 31 and between the filter cloths 34, 35. The diaphragm assembly l2, 13, 19 is fully pressurised, and filtration occurs through the filter cloths 34, 35; the wall member 21 is maintained in sealing engagement with the lower cloth 35 by the downward action of the ram 4 devices 11 and by the pressure of fluid acting on the shoulder 18 of the ring 10. The filtrate passes via the grooves in the diaphragm 19 and block 33 to the pipelines 47, 48, whence it is discharged. After filtration, the diaphragm assembly is deflated, and the ram devices 11 operate to move the wall member 21 clear of the bottom cloth 35 and so that the cloths 34, 35 can be moved through the passage 7. The cloth bands 34, 35 are advanced. to bring clean portions of cloth into the passage 7, the pressed cake being simultaneously removed from the pressby the lower moving bank 35. Prior to moving of thebands 34, 35', the grooves may be cleaned by the passage of air or cleaning fluid thereto through the pipelines 47, 48.

It may be desirable to surround the wall member 21 in a stretch nylon material sock to facilitate separation of it from the'pressed material, particularly inthe case of the press for moulding cementitious blocks. Conveniently this sock material could be a suitable length of material which is doubled over the wall member and has its edges tied together outside the wall member.

In a typical example, the diaphragms can be inflated by water pressurised'up to approximately 450 psi, or if pressure air is to be used, then this would be of up to a pressure of about p.s.i.

The above press has the following advantages:

i. The top and bottom sections 2, 3 are fixed: in previous presses these sections were movable to permit removal of the pressed material and additional guiding and lifting apparatus was consequently required.

'ii. The diaphragm assembly 12,13,19 occupies-the space between the sections 2 and 3, and is arranged, i.e. by the provision of the shoulder 18, to assist in maintaining a seal between the ring 10 and the wall member 21', and between the wall member 21 and the'lower section 3.

iii. The diaphragrns 12, 13 by their back-to-back arrangement are free standing and can contain the internal pressure on their own; the lower diaphragm l9 is supported by the material to be pressed and consequently does not require to be free standing. Rupture in the diaphragm is consequently mitigated. Also, the present diaphragm arrangement dispenses with a peripheral connection between the diaphragms, which connection was subject to failure.

iv. There is no friction between the diaphragms 12, 13 and the plates 7, 8.

We claim:

1. A press comprising a frame structure including a facing pair of spaced platens having facing surfaces; a receiving medium for material to be pressed extending across the facing surface of one of the platens, a fluid expansible device located between the platens and including a first flexible diaphragm connected to the other of the platens and forming a fluid chamber with said other platen, and 'an inflatable member between the first diaphragm and said one platen and comprising a second flexible diaphragm back-to-back with said first diaphragm and a third flexible diaphragm for pressing material on the receiving medium, the inflatable member and fluid chamber being in fluid communication; a peripheral wall structure located on the receiving medium below the inflatable member so that a pressing chamber is provided by the peripheral wall structure, the third diaphragm and the receiving medium; and inlet means to the expansible device for pressure fluid.

2. A press as claimed in claim 1, wherein means are provided to move said inflatable member towards and away from the said one platen.

3. A press as claimed in claim 2, wherein an intermediate ring structure is provided between the platens and said inflatable member is secured to the ring, and means are provided for moving the ring structure towards or away from said one platen, the peripheral wall structure being located between the ring structure and said one platen.

4. A press as claimed in claim 3, wherein the ring structure includes a shoulder for engagement by the inflatable member whereby a force is exerted on the shoulder by the inflatable member to assist in sealing engagement of the peripheral wall structure with the receiving medium when the wall structure is held against the receiving medium.

5. A press as claimed in claim 1, wherein the receiving medium is a filter medium and the third diaphragm has a filter medium thereon, the filter medium forming an envelope between said third diaphragm and said one platen.

6. A press as claimed in claim 5, wherein the filter mediums are endless bands trained around rollers outwith the press and provided with means for progressing it around the rollers.

7. A press as claimed in claim 6, wherein the progressing means include a releasable clamp mounted for reciprocal motion and adapted to grip the cloth on a forward movement to progress the cloth around the rollers.

8. A press as claimed in claim 7, wherein the progressing means comprises a pulley system including a reciprocal guide having a roller system for withdrawal of cloth on an advance movement of the guide, drive means for reciprocation of the guide, said clamp being mounted on the guide.

9. A press as claimed in claim 1, wherein the facing surface of said one platen and the side of the third diaphragm facing said one platen are grooved for drainage of expressed liquid.

10. A press as claimed in claim 3, wherein the means for moving the ring relative to said one platen comprise a plurality of piston-and-cylinder devices which when the press is in operation press a peripheral wall structure linked with the ring against the receiving medium.

11. A press as claimed in claim 3, wherein the periphery bounding the area of contact of the back-to-back diaphragms defines a greater area than that defined by the outer perimeter of contact of the ring structure with said one platen.

12. A press as claimed in claim 11, wherein the inner platen engaging surface of the peripheral wall structure includes a sealing ring and said periphery bounding the contact area of the back-to-back diaphragms defines a greater area than that defined by said sealing ring.

13. A press as claimed in claim 3, wherein an inlet for material to be pressed is provided through the peripheral wall structure to permit the pressing chamber to be filled with material to be pressed when the peripheral wall structure is in position below the inflatable member, the peripheral wall structure including shifting means to separate the peripheral wall structure from the receiving medium upon deflation of the expansible device and retraction of the ring upon completion of the pressing operation.

14. A press as claimed in claim 13, wherein the shifting means include apertured lugs attached to the outer periphery of the peripheral wall structure and engageable by the ring moving means.

15. A press as claimed in claim 1, wherein the peripheral wall structure is in the form of a block mould including an inner wall profiled to produce a block of desired peripheral shape, and the receiving medium is in the fonn of a drainage bed including a moulding station whereat the block mould is located.

16. A press as claimed in claim 15, wherein means are provided to move the mould to and from the moulding station.

17. A press as claimed in claim 16, wherein means are provided to fill the mould when the mould is outside the moulding station.

18. A press as claimed in claim 16, wherein the space between the said platens drainage provides an openended passage through the press and a conveyor belt in the fonnof a length of open mesh metal strip is.positioned on the drainage bed for support of the mould, the conveyor belt extending beyond the open-ended passage of the press and means being provided to move this belt into and out of the passage.

19. A press as claimed in claim 18, wherein lift means are provided outside the passage adapted to engage and separate the mould from the conveyor belt and the pressmoulded material. I

20. A press as claimed in claim 19, wherein the lift means comprise a number of extensible rams which can raise or lower the mould relative to the conveyor belt.

21. A press comprising a frame structure including a facing pair of spaced platens having facing surfaces; a receiving medium for material to be pressed extending across the facing surface of one of the platens; an intermediate ring between the platens; means for moving the ring towards or away from the said one platen; a fluid expansible device partly located between the other of the platens andthe intermediate ring and including a pressing diaphragm projecting into the aperture of the ring for pressing of material; inlet means for pressure fluid to the expansible device; the arrangement of the expansible device and ring being such that a peripheral shoulder is provided by the ring for the expansible device whereby on inflation of the expansible device a force is exerted on the shoulder; a peripheral wall structure arranged such that a pressing chamber is defined between the said pressing diaphragm of the expansible device, the receiving medium and the peripheral wall structure; the introduction of pressure fluid to the expansible device through the inlet means causing inflation of the expansible device to press material in the pressing chamber and to assist in sealing engagement of the peripheral wall structure with the receiving medium by means of the said force on the ring shoulder when the wall structure is held against the receiving medium. 

1. A press comprising a frame structure including a facing pair of spaced platens having facing surfaces; a receiving medium for material to be pressed extending across the facing surface of one of the platens, a fluid expansible device located between the platens and including a first flexible diaphragm connected to the other of the platens and forming a fluid chamber with said other platen, and an inflatable member between the first diaphragm and said one platen and comprising a second flexible diaphragm backto-back with said first diaphragm and a third flexible diaphragm for pressing material on the receiving medium, the inflatable member and fluid chamber being in fluid communication; a peripheral wall structure located on the receiving medium below the inflatable member so that a pressing chamber is provided by the peripheral wall structure, the third diaphragm and the receiving medium; and inlet means to the expansible device for pressure fluid.
 2. A press as claimed in claim 1, wherein means are provided to move said inflatable member towards and away from the said one platen.
 3. A press as claimed in claim 2, wherein an intermediate ring structure is provided between the platens and said inflatable member is secured to the ring, and means are provided for moving the ring structure towards or away from said one platen, the peripheral wall structure being located between the ring structure and said one platen.
 4. A press as claimed in claim 3, wherein the ring structure includes a shoulder for engagement by the inflatable member whereby a force is exerted on the shoulder by the inflatable member to assist in sealing engagement of the peripheral wall structure with the receiving medium when the wall structure is held against the receiving medium.
 5. A press as claimed in claim 1, wherein the receiving medium is a filter medium and the third diaphragm has a filter medium thereon, the filter medium forMing an envelope between said third diaphragm and said one platen.
 6. A press as claimed in claim 5, wherein the filter mediums are endless bands trained around rollers outwith the press and provided with means for progressing it around the rollers.
 7. A press as claimed in claim 6, wherein the progressing means include a releasable clamp mounted for reciprocal motion and adapted to grip the cloth on a forward movement to progress the cloth around the rollers.
 8. A press as claimed in claim 7, wherein the progressing means comprises a pulley system including a reciprocal guide having a roller system for withdrawal of cloth on an advance movement of the guide, drive means for reciprocation of the guide, said clamp being mounted on the guide.
 9. A press as claimed in claim 1, wherein the facing surface of said one platen and the side of the third diaphragm facing said one platen are grooved for drainage of expressed liquid.
 10. A press as claimed in claim 3, wherein the means for moving the ring relative to said one platen comprise a plurality of piston-and-cylinder devices which when the press is in operation press a peripheral wall structure linked with the ring against the receiving medium.
 11. A press as claimed in claim 3, wherein the periphery bounding the area of contact of the back-to-back diaphragms defines a greater area than that defined by the outer perimeter of contact of the ring structure with said one platen.
 12. A press as claimed in claim 11, wherein the inner platen engaging surface of the peripheral wall structure includes a sealing ring and said periphery bounding the contact area of the back-to-back diaphragms defines a greater area than that defined by said sealing ring.
 13. A press as claimed in claim 3, wherein an inlet for material to be pressed is provided through the peripheral wall structure to permit the pressing chamber to be filled with material to be pressed when the peripheral wall structure is in position below the inflatable member, the peripheral wall structure including shifting means to separate the peripheral wall structure from the receiving medium upon deflation of the expansible device and retraction of the ring upon completion of the pressing operation.
 14. A press as claimed in claim 13, wherein the shifting means include apertured lugs attached to the outer periphery of the peripheral wall structure and engageable by the ring moving means.
 15. A press as claimed in claim 1, wherein the peripheral wall structure is in the form of a block mould including an inner wall profiled to produce a block of desired peripheral shape, and the receiving medium is in the form of a drainage bed including a moulding station whereat the block mould is located.
 16. A press as claimed in claim 15, wherein means are provided to move the mould to and from the moulding station.
 17. A press as claimed in claim 16, wherein means are provided to fill the mould when the mould is outside the moulding station.
 18. A press as claimed in claim 16, wherein the space between the said platens drainage provides an open-ended passage through the press and a conveyor belt in the form of a length of open mesh metal strip is positioned on the drainage bed for support of the mould, the conveyor belt extending beyond the open-ended passage of the press and means being provided to move this belt into and out of the passage.
 19. A press as claimed in claim 18, wherein lift means are provided outside the passage adapted to engage and separate the mould from the conveyor belt and the pressmoulded material.
 20. A press as claimed in claim 19, wherein the lift means comprise a number of extensible rams which can raise or lower the mould relative to the conveyor belt.
 21. A press comprising a frame structure including a facing pair of spaced platens having facing surfaces; a receiving medium for material to be pressed extending across the facing surface of one of the platens; an intermediate ring between the platens; means for moviNg the ring towards or away from the said one platen; a fluid expansible device partly located between the other of the platens and the intermediate ring and including a pressing diaphragm projecting into the aperture of the ring for pressing of material; inlet means for pressure fluid to the expansible device; the arrangement of the expansible device and ring being such that a peripheral shoulder is provided by the ring for the expansible device whereby on inflation of the expansible device a force is exerted on the shoulder; a peripheral wall structure arranged such that a pressing chamber is defined between the said pressing diaphragm of the expansible device, the receiving medium and the peripheral wall structure; the introduction of pressure fluid to the expansible device through the inlet means causing inflation of the expansible device to press material in the pressing chamber and to assist in sealing engagement of the peripheral wall structure with the receiving medium by means of the said force on the ring shoulder when the wall structure is held against the receiving medium. 